The present invention relates to an organic electroluminescent device having an excellent luminance property such as high luminance efficiency.
An organic electroluminescent device (which will hereinafter be called xe2x80x9corganic EL devicexe2x80x9d) is a light-emitting device which makes use of the principle that when an electric field is applied, a fluorescent material emits light in response to the charge recombination of holes injected from an anode and electrons injected from a cathode. After C. W. Tang et al. of Eastman Kodak Company reported a low-voltage-driven organic EL device using a double layered structure (C. W. Tang, S. A. Vanslyke, Applied Physics Letters, Vol. 51, 913 (1987) and the like), studies on an organic EL device have been briskly carried out. Tang et al. reported an organic EL device using tris(8-hydroxyquinolinol aluminum) in a light-emitting layer and a triphenyldiamine derivative in a hole-transporting layer. This stacked structure gives such advantages as an improvement in the injection efficiency of holes into the light-emitting layer; and confinement of the excitons into the light-emitting layer.
A double layered structure composed of a hole-injecting and transporting layer and an electron-transporting and light-emitting layer or a triple layered structure composed of a hole-injecting and transporting layer, a light-emitting layer and an electron-injecting and transporting layer is well known as an organic EL device. In order to increase the recombination efficiency of injected holes and electrons, various improvements in the device structure or fabrication process have been introduced to such multi-layered devices.
As a hole transporting material, triphenyl amine derivatives and aromatic diamine derivatives such as 4,4xe2x80x24,4xe2x80x3-tris(3-methylphenylphenylamino)-triphenyl amine which is a star burst molecule and N,Nxe2x80x2-diphenyl-N,Nxe2x80x2-bis(3-methylphenyl)-[1,1xe2x80x2-biphenyl]-4,4xe2x80x2-diamine are well known (for example, Patent Publications JP-A-8-20771, JP-A-8-40995, JP-A-8-40997, JP-A-8-53397, and JP-A-8-87122). As an electron transporting material, oxadiazole derivatives, triazole derivatives and the like are well known.
Chelate complexes such as tris(8-quinolinolate)aluminum complex, coumarin derivatives, tetraphenylbutadiene derivatives, bis-styrylarylene derivatives, oxadiazole derivatives and the like are known as light emitting materials. Since various color lights in a visible region from blue to red are obtained from these light-emitting materials, there is increased expectation for industrialization of a full color organic EL device (refer to, e.g., JP-A-8-239655, JP-A-7-138561, and JP-A-3-200889).
Further, in addition to the above-mentioned compounds, diphenylaminoarylene having a styryl group has been discloses as a useful constituent material of an organic electroluminescent device having high ability (JP-A Nos. 11-74079, 11-185961 and the like).
However, some EL devices containing the diphenylaminoarylene compound show that the luminance decrease because of the concentration quenching caused by the intermolecular interactions.
Further, the chemical stability of a distyryldiarylaminoarylene would decrease when both of two aryl groups in the diarylamino group comprise a styryl group at the same time, so the luminescent properties, especially the durability of EL devices containing the distyryldiarylaminoarylene compound decrease.
It is therefore an object of the present invention to provide materials for the organic EL devices having excellent luminescent properties.
A first aspect of the present invention for attaining this object is an organic electroluminescent device comprising one or more organic thin film layer(s) placed between an anode and a cathode, at least one of said layer being a luminescent layer,
characterized in that said luminescent layer comprises a compound expressed in the following general formula [1.1] in the form of a single substance or a mixture containing the same. 
(wherein, Ar1 represents a substituted or unsubstituted arylene group having 5 to 42 carbon atoms; at least one of Ar2 to Ar5 independently represents a group expressed in the following general formula [1.2]; the remaining group(s) of Ar2 to Ar5 independently represents an aryl group having 6 to 20 carbon atoms; and at least one of Ar2 to Ar5 comprises at least one hydrocarbon group which may include oxygen atom(s). Ar2 and Ar3 and/or Ar4 and Ar5 may mutually bond to form a ring.) 
(wherein, each of R1 to R11 independently represents a hydrogen atom, halogen atom, hydroxyl group, substituted or unsubstituted amino group, cyano group, nitro group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkoxycarbonyl group, or carboxyl group. Two of R1 to R11 may form a ring.)
A second aspect of the present invention is an organic electroluminescent device comprising one or more organic thin film layer(s) placed between an anode and a cathode, at least one of said layer being a luminescent layer,
characterized in that said luminescent layer comprises a compound expressed in the following general formula [2.1] in the form of a single substance or a mixture containing the same. 
(wherein, Ar1 represents a substituted or unsubstituted arylene group having 5 to 42 carbon atoms; at least one of Ar1 to Ar5 independently represents a group expressed in the following general formula [2.2]; the remaining group(s) of Ar2 to Ar5 independently represents an aryl group having 6 to 20 carbon atoms; and at least one of Ar2 to Ar5 comprises at least one saturated hydrocarbon group having 2 or more carbon atoms in which oxygen atom(s) may be inserted. Ar2 and Ar3 and/or Ar4 and Ar5 may mutually bond to form a ring.) 
(wherein, each of R1 to R11 independently represents a hydrogen atom, halogen atom, hydroxyl group, substituted or unsubstituted amino group, cyano group, nitro group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkoxycarbonyl group, or carboxyl group. Two of R1 to R11 may form a ring.)
There is also provided an organic electroluminescent device comprising at least an anode, a luminescent zone and a cathode, the luminescent zone being formed from one or more organic thin film layer(s),
characterized in that the above-mentioned luminescent zone is adjacent to the anode, and a layer adjacent to the anode of the organic thin film layer(s) forming the luminescent zone contains a compound expressed in the above-described general formula [2.1] in the form of a single substance or a mixture containing the same.
A third aspect of the present invention is an organic electroluminescent device comprising one or more organic thin film layer(s) placed between an anode and a cathode, at least one of said layer being a luminescent layer,
characterized in that said luminescent layer comprises a compound expressed in the following general formula [3.1] in the form of a single substance or a mixture containing the same. 
(wherein, Ar1 represents a substituted or unsubstituted arylene group having 5 to 42 carbon atoms; each of Ar2 and Ar3 independently represents a group expressed in the following general formula [3.2]; and each of Ar4 and Ar5 independently represents substituted or unsubstituted aryl group having 6 to 20 carbon atoms. Ar2 and Ar3 and/or Ar4 and Ar5 may mutually bond to form a ring.) 
(wherein, each of R1 to R11 independently represents a hydrogen atom, halogen atom, hydroxyl group, substituted or unsubstituted amino group, cyano group, nitro group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted cycloalkyl-group, substituted or unsubstituted alkoxy group substituted or unsubstituted aromatic hydrocarbon group, substituted or unsubstituted aromatic heterocyclic group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryloxy group, substituted or unsubstituted alkoxycarbonyl group, or carboxyl group; and R6 is a substituent other than a hydrogen atom. Two of R1 to R11 may form a ring.)
There is also provided an organic electroluminescent device comprising at least an anode, a luminescent zone and a cathode, the luminescent zone being formed from one or more organic thin film layer(s),
characterized in that the above-mentioned luminescent zone is adjacent to the anode, and a layer adjacent to the anode of the organic thin film layer(s) forming the luminescent zone contains a compound expressed in the above-described general formula [3.1] in the form of a single substance or a mixture containing the same.